#!/bin/sh
set -e

usage() {
    argv0=$(basename $0)

    cat >&2 << END
Usage:
For comparing files created my cairo-perf:

	$argv0 old.perf new.perf

For comparing (cached) performance of revisions:

	$argv0 [OPTIONS] <revision> [-- cairo-perf options]
	$argv0 [OPTIONS] <rev1> <rev2> [-- cairo-perf-options]

If given a single revision, compares its results to that of its
(first-parent) predecessor. Otherwise compares the two given revisions.
The revisions can be any revision accepted by git. For example:

	$argv0 HEAD		# Show impact of latest commit
	$argv0 1.2.0 1.2.4	# Compare performance of 1.2.0 to 1.2.4

Options:

-f, --force
	Forces cairo-perf-diff to re-run performance tests
	even if cached performance data is available.

-h, --html
	With this option performance changes are summarized
	as HTML table.

Additional options can be passed the child cairo-perf process
by separating them with a double hyphen (--). For example, to
examine what the impact of the latest change is on the stroke
test you might use:

	$argv0 HEAD -- stroke

The performance results are cached in .perf next to the .git directory.

Set CAIRO_AUTOGEN_OPTIONS to pass options to autogen for both
builds.
END

    exit 1
}

# Yes, this ugly ad-hoc option parsing could be cleaned up
if [ $# -eq 0 ] || [ "$1" = "--" ]; then
    usage
fi

while true; do
    case $1 in
        -f|--force) force_cairo_perf="true";;
        -h|--html) html_output="true";;
        *) break;;
    esac

    shift
done

if [ $# -eq 1 ] || [ "$2" = "--" ]; then
    old="$1^"
    new="$1"
    shift 1
else
    old="$1"
    new="$2"
    shift 2
fi

CAIRO_PERF_OPTIONS="-r -i 10"
if [ $# -gt 0 ]; then
    if [ "$1" = "--" ]; then
	shift 1
	CAIRO_PERF_OPTIONS="$CAIRO_PERF_OPTIONS $@"
    else
	usage
    fi
fi

git_setup() {
    SUBDIRECTORY_OK='Yes'
    . git-sh-setup
    CAIRO_DIR=$(dirname $GIT_DIR)
    if [ "$CAIRO_DIR" = "." ]; then
	CAIRO_DIR=$(pwd)
    fi
    CAIRO_PERF_DIR=$CAIRO_DIR/.perf
}

rev2sha() {
    rev=$1
    git rev-parse --verify $rev || ( echo "Cannot resolve $rev as a git object" && exit 1 )
}

cpu_count() {
    test -f /proc/cpuinfo &&
    grep -c '^processor[[:blank:]]\+:' /proc/cpuinfo ||
    echo 1
}

# We cache performance output based on a two-part name capturing the
# current performance test suite and the library being tested. We
# capture these as the tree object of the perf directory in HEAD and
# the tree object of the src directory of the revision being tested.
#
# This way, whenever the performance suite is updated, cached output
# from old versions of the suite are automatically invalidated. Also,
# if a commit just changes things outside of the src tree, (say it
# changes the "test" test suite, or README or configure.in, or
# whatever), cairo-perf-diff will be smart enough to still use cached
# results from a run with an equivalent src tree.
rev2perf() {
    rev=$1
    src_tree_sha=$(rev2sha $rev:src)
    pxm_tree_sha=$(rev2sha $rev:pixman/src)
    perf_tree_sha=$(rev2sha HEAD:perf)
    echo "$CAIRO_PERF_DIR/${perf_tree_sha}-${src_tree_sha}-${pxm_tree_sha}.perf"
}

# Usage: run_cairo_perf_if_not_cached <rev> <suffix>
# The <rev> argument must be a valid git ref-spec that can
# be resolved to a commit. The suffix is just something
# unique so that build directories can be separated for
# multiple calls to this function.
run_cairo_perf_if_not_cached() {
    rev=$1
    build_dir="build-$2"

    owd=$(pwd)
    sha=$(rev2sha $rev)
    perf=$(rev2perf $rev)
    if [ -e $perf ] && [ "$force_cairo_perf" != "true" ]; then
	return 0
    fi
    if [ ! -d $CAIRO_PERF_DIR ]; then
	echo "Creating new perf cache in $CAIRO_PERF_DIR"
	mkdir $CAIRO_PERF_DIR
    fi

    cd $CAIRO_DIR
    boilerplate_files=$(git ls-tree --name-only HEAD boilerplate/*)
    perf_files=$(git ls-tree --name-only HEAD perf/*)
    cd $CAIRO_PERF_DIR

    if [ ! -d $build_dir ]; then
	git clone -s $CAIRO_DIR $build_dir
	(cd $build_dir; git checkout -b tmp-cairo-perf-diff $sha)
    fi
    cd $build_dir

    git checkout tmp-cairo-perf-diff
    git reset --hard $sha

    if [ -z "$MAKEFLAGS" ]; then
        export MAKEFLAGS="-j$(expr $(cpu_count) + 1)"
    fi

    if [ ! -e Makefile ]; then
	CFLAGS="-O2" ./autogen.sh $CAIRO_AUTOGEN_OPTIONS
    fi
    make CFLAGS="-O2" || (rm config.cache && make CFLAGS="-O2")
    for file in $boilerplate_files; do
	rsync $CAIRO_DIR/$file boilerplate
    done
    (cd boilerplate; make)
    for file in $perf_files; do
	rsync $CAIRO_DIR/$file perf
    done
    cd perf;
    make || exit 1
    echo "Running \"cairo-perf $CAIRO_PERF_OPTIONS\" against $rev. Results will be cached in:"
    echo "$perf"
    (./cairo-perf $CAIRO_PERF_OPTIONS || echo "*** Performance test crashed") >> $perf
    cd $owd
}

if [ ! -e $old ]; then
    git_setup
    run_cairo_perf_if_not_cached $old old
    old=$(rev2perf $old)
fi

if [ ! -e $new ]; then
    git_setup
    run_cairo_perf_if_not_cached $new new
    new=$(rev2perf $new)
fi

if [ "$html_output" != "true" ]; then
    $CAIRO_DIR/perf/cairo-perf-diff-files $old $new
else
    $CAIRO_DIR/perf/cairo-perf-diff-files $old $new |
    $CAIRO_DIR/perf/make-html.py
fi